Pokémon-GX are a special kind of card. Like Pokémon EX, if defeated then the player can take two prize cards. However, Pokémon-GX have got a special advantage; They have GX attacks. You are only allowed to use one GX attack per game, meaning that even if you have multiple cards with GX attacks, you can only use one. This is in parallel to the Z Moves in the main game